Statistical optimization of biohydrogen fermentation from a perspective of butyrate production

Abstract

Optimization of additives was achieved for hydrogen and butyric acid production modelled through a three-level Box-Behnken Design of the response surface methodology. Seventeen runs were designed with variables of sodium chloride (0.1–5 g/L), sodium thiosulphate (0–200 mg/L) and minerals (Zinc, iron, cupper and nickel (0–0.8 mM). The model fit to a cubic model with a high R2 of 96% and P value of 0.03. Some of the interactive variables have significant effect on butyrate production. The butyrate concentrations were close to the predicted ones. The model showed that higher butyric acid concentrations were observed with low sodium chloride and high sodium thiosulphate and minerals concentrations. Butyrate/Acetate ratios (BA/A), hydrogen production yield and rates increased with mean values of the independent variables. A cumulative hydrogen formation of 155 mL, yield of 2.6 mmol H2/mmol lactose, and rate of 3.6 mL/g/h was observed with the highest BA/AA ratio obtained from experiments.